In some wireless communication systems, user equipments (UEs) wirelessly communicate with one or more base stations. The wireless communications may be performed by transmitting orthogonal frequency-division multiplexing (OFDM) symbols, which may be transmitted according to an orthogonal multiple access scheme such as orthogonal frequency-. division multiple access (OFDMA), or a non-orthogonal multiple access (NoMA) scheme such as sparse code multiple access (SCMA).
A wireless communication from a UE to a base station referred to as an uplink communication. A wireless communication from a base station to a UE is referred to as a downlink communication. Resources are required to perform uplink and downlink communications. For example, a base station may wirelessly transmit data to a UE in a downlink communication at a particular frequency for a particular duration of time. The frequency and time duration are examples of resources.
Some UEs served by a base station may need to receive data from the base station and/or transmit data to the base station with low latency, for example by keeping (uplink and/or downlink) transmissions within 0.5 ms or the overall end-to-end (or return) latency within 1 ms. For example, a base station may serve multiple UEs, including a first UE and a second UE. The first UE may be a mobile device carried by a human who is using the first UE to browse on the Internet. The second UE may be equipment on an autonomous vehicle driving on a highway. Although the base station is serving both UEs, the second UE may need to send and/or receive data with lower latency compared to the first UE. The second UE may also need to send and/or receive its data with high reliability. The second UE may be an ultra-reliable low latency communication (URLLC) UE, whereas the first UE may be an enhanced mobile broadband (eMBB) UE.
UEs that are served by a base station and that require lower latency communication will be referred to as “low latency UEs”. The other UEs served by the base station will be referred to as “latency tolerant UEs”. Data to be transmitted between a base station and a low latency UE will be referred to as “low latency data”, and data to be transmitted between a base station and a latency tolerant UE will be referred to as “latency tolerant data”. It is contemplated that a single UE might use both low latency communication and latency tolerant communication, in which case the term “low latency UE” would refer to the activities of the single UE for the purpose of low latency communication and the term “latency tolerant UE” would refer to the activities of the single UE for the purpose of latency tolerant communication.
It is desired to accommodate the presence of both low latency and latency tolerant communications in shared time-frequency resources to improve resource utilization.